NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header

Explorer 3



Explorer 3 (1958 Gamma 1) was launched in conjunction with the IGY by the U.S. Army (Ordinance) into an eccentric orbit. The objective of this spacecraft was a continuation of experiments started with Explorer 1. The payload consisted of a cosmic ray counter (a Geiger-Mueller tube), and a micrometeorite detector (erotion gauge). The Explorer 3 spacecraft was spin stabilized and had an on-board tape recorder to provide a complete radiation history for each orbit. It was discovered soon after launch that the satellite was in a tumbling motion with a period of about 7 s. Explorer 3 decayed from orbit on June 27, 1958, after 93 days of operation.

Alternate Names

  • 1958 Gamma 1
  • 00006
  • Explorer3

Facts in Brief

Launch Date: 1958-03-26
Launch Vehicle: Juno
Launch Site: Cape Canaveral, United States
Mass: 14.1 kg

Funding Agency

  • Department of Defense-Department of the Army (United States)


  • Space Physics
  • Astronomy

Additional Information

Questions and comments about this spacecraft can be directed to: Coordinated Request and User Support Office

[] NASA Logo -